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13th Annual Conference of the British HIV Association29 March–1 April 2007, Brighton, UK |
AN INVESTIGATION INTO THE FREQUENCY AND REASONS WHY PATIENTS SWITCH ANTIRETROVIRAL THERAPY AND WHICH ANTIRETROVIRALS ARE IMPLICATED WHEN SWITCHING BECAUSE OF TOXICITY: THE CHELSEA SWITCH INVESTIGATION (CSI) DATA
HIV Med 2007; 8(Suppl. 1):7 (abstract no. O25)
Iain Davidson, Helen Beardsell, Brian Smith, Brian Gazzard and Mark Nelson
St Stephen’s Centre, Chelsea and Westminster Hospital, London, UK
PURPOSE OF THE STUDY: To determine the rate that patients switch their antiretroviral therapy, why they switch and to calculate an observed toxicity switch rate for each antiretroviral.
METHODS: Outpatients’ prescriptions from the HIV cohort between 1st May and 31st Oct ‘06 were reviewed. All prescriptions involving a switch in antiretroviral therapy were recorded with details of which antiretrovirals were switched and the reason.
SUMMARY OF RESULTS: A total of 14% (n=469) of regimens were switched over the 6-month period affecting 13% (n=433) of patients. Excluding the tenofovir/lamivudine to truvada switches, this rate falls to 10% of patients in 6 months. The reasons for switch (excluding switches of tenofovir/lamivudine to truvada and switches because of the tenofovir/didanosine drug interaction) were 61% toxicity, 14% failure, 13% simplification, 4% drug interaction and 8% other (including pregnancy and hepatitis). Of the 202 switches for toxicity 44% were due to zidovudine (85/88 due to actual/potential lipodystrophy), 9% tenofovir (18/19 renal complications), 8% stavudine (14/16 actual/potential lipodystrophy), 8% efavirenz (15/16 CNS side-effects), 5% Kaletra (7/10 diarrhoea), 4% saquinavir (9/9 GI side-effects), 4% atazanavir (7/8 jaundice) and 4% abacavir (5/8 suspected/actual HSR). An observed toxicity switch rate (OTSR) per 1000 patient years (95% CI) was calculated for each antiretroviral (table 1).
| NRTIs | OTSR (95% CI) | PIs | OTSR (95% CI) |
| Stavudine | 304.9 (174.3–495.1) | Fosamprenavir | 89.5 (10.8–323.5) |
| Zidovudine | 224.6 (180.2–276.8) | Saquinavir | 81.2 (37.1–154.0) |
| Didanosine | 27.6 (9.0–64.4) | Kaletra | 46.9 (22.5–86.2) |
| Tenofovir | 19.8 (11.9–30.9) | Atazanavir | 27.0 (11.7–53.2) |
| Abacavir | 15.1 (6.5–29.7) | NNRTIs | |
| Emtricitabine | 9.9 (3.2–23.0) | Efavirenz | 24.7 (14.1–40.1) |
| Lamivudine | 1.2 (0.03–6.5) | Nevirapine | 15.8 (4.3–40.4) |
CONCLUSIONS: Ten percent of patients switched therapy in 6 months predicting that one in five patients will change their therapy every year. Stavudine and Zidovudine have a significantly higher OTSR than the other nucleoside/nucleotide analogues. There is no significant difference in the OTSR with the NNRTIs or the PIs.
2007-03-29
O25
Copyright © 2007 - British HIV Association (BHIVA) Reproduction of this abstract (other than one copy for personal reference) must be cleared through the BHIVA Organising Secretariat 1 Mountview Court, 310 Friern Barnet Lane, London N20 0LD